The incidence of maize stunt diseases, or achaparramiento, rose in Nicaragua from an
insignificant level to national crisis proportions, then declined to insignificant levels again, all
in the space of 10 yr. The 3 pathogens that cause achaparramiento, corn stunt spiroplasma,
maize bushy stunt phytoplasma, and maize ray ado fino virus are transmitted by the corn
leafhopper, Dalbulus maidis (De-Long & Wolcott). Vector populations did not change
sufficiently over time to explain the epidemic pattern. Nor did changes in the varieties of …